External fixation is a surgical treatment used to set bone fractures in which a cast would not allow proper alignment of the fracture. In this kind of reduction, holes are drilled into uninjured areas of bones around the fracture and special bolts or wires are screwed or otherwise advanced into the holes. Outside the body, a rod or a curved piece of metal with special joints joins the bolts to make a rigid support. External fixation is usually used when internal fixation is contraindicated, often to treat open fractures, or as a temporary solution.
There are two main types of external fixation. One is known as mono-lateral fixation where the metal external structure is on one side of the limb. The other is circular fixation, in which the metal structure is circular or an arch and surrounds the limb. Installation of the external fixator is performed in an operating room, normally under general anesthesia. Removal of the external frame and bolts can be done with no anesthesia in an office visit. Circular fixation external fixators are often used for fractures of long bones that are weight bearing such as the femur and tibia. It is known that bearing weight through a fracture by walking on it, for example, with the added support of the external fixator frame actually helps fractures to heal.
Circular fixation external fixators typically include at least one ring. The ring surrounds the limb, for example the leg. Rods or distractors are connected to the ring and may engage a second, spaced apart, ring. Bone engaging pins are mounted onto the rings and/or the rods. The pins extend inwardly through soft tissue including skin and muscle and engage the bone near the fracture site. The pins may engage only the outer cortical bone or engage cancellous bone as well and may extend entirely through the bone. Adjustable clamps are used to connect the pins to the rods and to connect rods to each other at adjustable angular orietations.
Mono-lateral fixators typically include at least one bar onto which pins that similarly engage bone are secured by adjustable clamps similar those used in circular fixation external fixators. Bars may also be connected to each other by clamps. The clamps secure components such as the pins and the bars. The clamps include first jaws for grasping the bar and second jaws for grasping the pin or another bar. The components are aligned by partially tightening the clamps and lightly holding the jaws against the components while permitting the second jaw to move relative the first jaws and the components to slide within the jaws. The tightness of the jaws must be set very accurately to avoid having the components separate from the jaws of the clamps while positioning the components into the desired orientation. The components may also slip while tightening them into the final desired position. Since the pins must engage bone located below soft tissue, the proper positioning of the pins is difficult. The orienting of the components and rigid assembly of the fixator can be very challenging.
This time consuming difficult partial tightening of the fasteners and the exacting orientation of the components makes the surgery in which external fixators are installed slow and expensive and exposes the patient to risks associated with longer surgical procedures. Therefore, it would be advantageous to provide an improved external fixator.